1. Technical Field
The present invention relates to an apparatus for inflating an inflatable vehicle occupant protection device, such as an air bag. In particular, the present invention relates to an air bag inflator including a container having a rupturable portion, such as a burst disk.
2. Description of the Prior Art
A known type of inflator for inflating an air bag includes a container in which inflation fluid is stored under pressure. The container has a rupturable portion, such as a burst disk covering an opening in a wall portion of the container. The pressurized fluid in the container acts on an inner side surface of the burst disk. An opposite outer side surface of the burst disk is at ambient pressure. Upon actuation of the inflator, the burst disk is ruptured, by increased fluid pressure in the container, to release inflation fluid to flow into the air bag.
The burst disk typically includes one or more predetermined weakened portions, such as score lines formed on the burst disk, to facilitate controlled rupturing of the burst disk. The burst disk will rupture at a first pressure differential when it has score lines only on its inner side surface (exposed to pressurized fluid in the container). The burst disk will rupture at a second, different, pressure differential, when it has score lines only on its outer side surface. A burst disk with score lines on only one side must be oriented properly during assembly of the inflator, to ensure that it ruptures at a desired, predetermined container pressure. That is, the burst disk must be assembled in the inflator with one side, and not the other, exposed to the pressurized fluid in the container.
The present invention is an apparatus for inflating an inflatable vehicle occupant protection device. The apparatus comprises a container defining a chamber. The container has an opening through which fluid can flow from the chamber. A quantity of inflation fluid is in the chamber. A burst disk closes the opening. The burst disk has first and second opposite major side surfaces. The burst disk has a first score line on the first major side surface and a second score line on the second major side surface. The burst disk is rupturable at the first and second score lines to permit inflation fluid to flow out of the chamber through the opening in the container.